Aramid and aramid blend fabrics designed for filter bag have been known for sometime. In many of the application where filter bags are used, cartridge filters could provide a more efficient means of filtration, but the fabrics available for high temperature gas filtration have heretofore lacked the required durability and flexibility for industrial performance that equals that of filter bags.
Fabrics designed for filter bags are generally based on felts such as is described in U.S. Pat. No. 5,171,339. These felts are generally too heavy and stiff when used in a cartridge filter. Such fabrics are prone to break or tear open when the cartridge is pulsed with back pressure to remove particles that have been caught on the filter fabric surface. Lighter weight filter fabrics such as those taught in U.S. Pat. No. 4,536,439 do not have the inherent stiffness to be used in a cartridge filter application.
International Publication No. WO 96/24431 taught a fabric that could be formed into rigid shapes, but this publication did not address the balance of fabric flexibility and stiffness needed in order to make a durable, long service life cartridge filter for hot gas filtration.
It is the object of the present invention to provide a fabric for use in cartridge filters for hot gas filtration applications that has a balance of flexibility and stiffness combined with high filter efficiency.